At a time of driving a vehicle, it is necessary to confirm surroundings of the vehicle including the right and left directions of the vehicle in addition to a driving direction. It has been known that a blind spot for a drive may exist when the driver perceives vehicle surroundings by a side mirror or a back mirror mounted on a vehicle. Especially for a beginner driver, a driving through the alley with buildings on both sides, a passing by an oncoming car on the small road, and the like may be a great stress. Thus, a camera for capturing an area of the blind spot is mounted on a vehicle and displays that captured image on a monitor, thereby assisting perception of vehicle surroundings.
For example, according to JP2001-39232A, a right camera for capturing a front right side of a vehicle and a left camera for capturing a front left side of a vehicle are mounted on a vehicle. The captured images by the right camera and the left camera are displayed simultaneously on a monitor, beg arranged in parallel on right and left sides, respectively. In such a surroundings monitoring system for a vehicle, both areas of the front right side and the front left side of the vehicle can be perceived only by one monitor screen. However, as is easily understood from FIG. 1 of JP2001-39232A, when an image of a vehicle passing from the left side to the right side is captured by the cameras, the vehicle appears, first, on a left half portion of the monitor screen, as moving from a top left to a bottom right and then, suddenly, on a right half portion of the monitor screen, as moving from a bottom left to a top right. Thus, a movement of the vehicle passing as a surrounding object is unnatural and may cause a difference in direction and depth between the images from the right and left cameras, which may lead to difficulty in perception of surroundings by a driver.
In order to solve the aforementioned problem, according to JP2005-178508A, a camera provided at a vehicle captures vehicle surroundings while moving, and the captured image is sequentially displayed in response to an image captured area on a display device with a curved display screen in a state in which an image capturing direction corresponds to the display screen. In such a surroundings monitoring system, it is easy for a driver or a user to intuitively recognize a direction and a distance. However, expensive components such as a moving mechanism of a camera, an image processing unit for synchronizing the movement of the camera and a display on the curved screen, and the monitor with a curved surface are required, which may be a large issue for a manufacturing cost and a maintenance cost.
According to the surroundings monitoring system using a camera mounted on a vehicle, a driver seated on a vehicle seat perceives a blind spot through captured images by multiple cameras mounted on different locations of a vehicle. In this case, it is important to reduce differences in a direction and a distance among the captured images by these cameras. If a standard point as an important indicator at a time of the vehicle in motion can be captured by each camera, the standard point can be used as a target for synthesizing images, thereby reducing the differences in a direction and a distance among the captured images. However, an arrangement of the cameras that can capture the standard point is very difficult when considering various restrictions of mountings.
Thus, a need exists for a surroundings monitoring system for a vehicle with a simple configuration that can appropriately synthesize images obtained from imaging surfaces of multiple cameras mounted at different locations on a vehicle even if a standard point as an important indicator at a time of a vehicle in motion cannot be captured by all cameras so that a difference in direction and depth among the images captured by the respective cameras can be reduced when monitoring with the synthesized image.